Teaching and Developing about ?
Passing out of the post, Playing in his System ? He came in with 19 years of age, but he developed nothing new to play inside team basketball, a coach has to teach this, especially when you are dealing with young and raw Big-Man.
Kanter has not needed to learn about rebounding the ball, he was already elite at it coming into the league. But he got even worse on that and startet rebounding like a shooting guard...
Kanter has great work ethic and he is learning very fast when you consider him as a guy starting to play basketball with the age of 14. If this guy is getting worse then before, than the coach did somethin wrong the last two years.
If you enter the NBA needing a coach to teach you how to play, you're ****ed. You better hire a personal coach during the off season. NBA coaches DO NOT teach people how to play basketball. That would be like your manager at your new accounting job teaching you math.